Move URLLoaderClientImpl to a separate file

content/child/url_response_body_consumer.cc

Index: content/child/url_response_body_consumer.cc
diff --git a/content/child/url_response_body_consumer.cc b/content/child/url_response_body_consumer.cc
index 9d5c017d6e35597d4c6a9813dca9866a60f8f149..97484af53ebf4ccccaf234dd9d9f69f4eab48822 100644
--- a/content/child/url_response_body_consumer.cc
+++ b/content/child/url_response_body_consumer.cc
@@ -76,6 +76,15 @@ void URLResponseBodyConsumer::Cancel() {
   handle_watcher_.Cancel();
 }
 
+void URLResponseBodyConsumer::SetDefersLoading() {
+  is_deferred_ = true;
+}
+
+void URLResponseBodyConsumer::UnsetDefersLoading() {
+  is_deferred_ = false;
+  OnReadable(MOJO_RESULT_OK);
+}
+
 void URLResponseBodyConsumer::Reclaim(uint32_t size) {
   MojoResult result = mojo::EndReadDataRaw(handle_.get(), size);
   DCHECK_EQ(MOJO_RESULT_OK, result);
@@ -89,17 +98,17 @@ void URLResponseBodyConsumer::Reclaim(uint32_t size) {
 }
 
 void URLResponseBodyConsumer::OnReadable(MojoResult unused) {
-  DCHECK(!is_in_on_readable_);
-
-  if (has_been_cancelled_ || has_seen_end_of_data_)
+  if (has_been_cancelled_ || has_seen_end_of_data_ || is_deferred_)
     return;
 
+  DCHECK(!is_in_on_readable_);
+
   // Protect |this| as RequestPeer::OnReceivedData may call deref.
   scoped_refptr<URLResponseBodyConsumer> protect(this);
   base::AutoReset<bool> is_in_on_readable(&is_in_on_readable_, true);
 
   // TODO(yhirano): Suppress notification when deferred.
-  while (!has_been_cancelled_) {
+  while (!has_been_cancelled_ && !is_deferred_) {
     const void* buffer = nullptr;
     uint32_t available = 0;
     MojoResult result = mojo::BeginReadDataRaw(